An arrow board is a sign board having an arrowhead visibly featured on it. The arrowhead may be formed by reflective material or flashing lamps. Arrow boards are used to warn motorists of obstructions in the road and to direct the motorists around these obstructions. These obstructions may be road work crews, utility vehicles and the like.
Arrow boards are known in the art. In U.S. Pat. No. 3,622,980 an arrow board is disclosed in which a plurality of lamps are mounted on a board and are arranged in two interleaved groups. Each group defines at least three arrowheads aligned behind one another, with the arrowheads in each group being opposed in direction. The arrow board is mounted on a truck or trailer and is powered by a portable generator or by the truck's alternator. In use, the lamps forming an arrowhead flash on in succession for each arrowhead in the group. A similar device is disclosed in U.S. Pat. No. 3,883,846 but having an arrangement of lamps which is slightly different.
A problem with the prior art arrow boards is the security of operation. The arrangement of lamps illuminated to create an arrowhead is generally controlled by a simple two-way switch or the like. Switching the switch in one direction creates an arrowhead in that direction while switching the switch in the opposite direction creates an arrowhead in the opposite direction. Therefore, it may occur that the switch is accidentally switched in the wrong direction without the operator becoming aware of the problem.
Accordingly, it is an object of this invention to provide an arrow board which at least overcomes some of the problems associated with the prior art.